1. Field of the Invention
The present invention relates to a list management server for managing the updating of a list of information provider terminals which are monitored by receiver terminals, a list management system, a list managing method, and a program, and more particularly to a list management server for managing the updating of a list by a third-party terminal, a list management system, a list managing method, and a program. The list is used to distribute information owned by information provider terminals to receiver terminals.
2. Description of the Related Art
Heretofore, there have been known presence systems for managing user statuses. For example, JP-A-2004-246397 discloses a presence system employing a buddy list. The buddy list represents a list of persons whose statuses are to be monitored.
A presence system is a term describing a presence service that is supported by a system for managing the state of each user. The basic architecture of the presence system is described by RFC (Request For Comment) 2778.
A presence system includes a presentity, a watcher, and a presence service.
The presentity holds the status of a status information provider, i.e., the presence information of a status information provider. Specifically, the presentity is a terminal device for holding the presence information of a status information provider.
The watcher provides the presence information held by a presentity to a status information receiver. Specifically, the watcher is a terminal device for accepting the presence information owned by a presentity.
If there is a plurality of presentities, a watcher does not accept the presence information of all the presentities, but accepts the presence information of the presentity that the watcher has designated.
The presentity that the watcher has designated is referred to as a buddy (an entity to be monitored). The watcher generates a buddy list of buddies (an information monitored entity list) in order to acquire the presence information of buddies.
The presence service distributes the presence information of a buddy represented by a buddy list to a watcher.
JP-A-2002-91893 discloses a workflow system for allowing a plurality of terminal devices interconnected by a network to sequentially update a single electronic file.
According to the disclosed workflow system, when a terminal device finishes updating the electronic file, it hands over its authority to update the electronic file to another terminal device.
A terminal device can recover the authority to update the electronic file that the terminal device has lost. The terminal device can recover the updating authority even in the absence of the consent from the user of the terminal device that is currently holding the updating authority.
Specifically, the terminal device can take back the updating authority by issuing a request to recover the updating authority.
In an ordinary presence system (presence service), only a watcher (in this case, an information receiver) and a presence service administrator (hereinafter referred to simply as “administrator”) have an authority to update the buddy list of the watcher.
If a third party which is neither the watcher nor the administrator wants to update the buddy list of the watcher, then the third party has to request the watcher or the administrator to update the buddy list, and the watcher or the administrator has to update the buddy list according to the request.
Consequently, unless the watcher or the administrator updates the buddy list of the watcher, the third party cannot update the buddy list.
When the watcher or the administrator is requested by the third party to update the buddy list, the watcher or the administrator needs to take the trouble of updating the buddy list according to the request.
JP-A-2002-91893 discloses a workflow system that allows a terminal device that is free of the updating authority to acquire the updating authority by issuing a request to recover the updating authority.
According to the disclosed workflow system, the updating authority is transferred to the terminal device that has issued the request to recover the updating authority even if there is no consent from the user of the terminal device that is currently holding the updating authority.
Consequently, if the updating authority transference technology is applied to a presence system (presence service), then a malicious third party may rewrite the buddy list for unauthorized acquisition of the presence information of a certain buddy.